Newly rebuilt 4L60E dead at 750 miles!?

[Pyromaniacal]

I got in my newly built boosted LT1 stroker today, turned out of my neighborhood onto a 55mph road and accelerate pretty healthily 0-60 upon hitting 60 in 2nd gear and letting off the gas to influence a shift to OD, the RPM began to hang and then fell to idle levels (2100...) I could free rev as if I was in neutral but I was most certainly in drive, the car would not accelerate unless I rose the RPM above 4500 RPM or slowed down. When I stopped completly, the RPM began to fluctuate between 1900-2100 until I turned it off and restarted it.

So here I am now, about to freak out because my newly rebuilt 4L60E (750 MILES!!!) is quite possibly heading out to pasture ALREADY... I know a few people on here have blown some of these so I really need a helping hand in diagnosing the problem. Is the tranny gone? Or perhaps another problem?

If this fucker really is gone, I am sticking a 6 speed in this thing... any info on some good T-56 guys that can built a 6 speed capable of handling 750+ ft-lbs would also be GREATLY appreciated as I may do this whether or not the 4L60E is dead.

Thanks to anyone who can offer me some advice, I really need it rofl.

[bigrondownhiller]

I would take it back to whoever rebuilt it. was the torque converter rebuilt?

[Zboner]

ditch the auto i went through 7 of them in 6 months

[Pyromaniacal]

Wow, quite a few autos in a short amount of time, I would have been freaking out at the guys building that shit.

I am going to be giving him a call in a little bit and gettin' to the bottom of this. The TC was actually put in not even 2 weeks ago, downgrade from a 4500 stall (barely street driveable rofl) to a 2400, problems started immediately after that. Very hard 1-2 shift ever since the change, as well. I was thinking it may have been a computer issue, the car's computer was tuned by PCMForless. Apparently these guys are about as smart as the bolts holding the car together and tuned it like a bunch of apes, the thing runs like shit! A/F is totally out of control, if its not leaning out completly and stalling out at low speeds, its running so rich that I'm getting a beautiful 8 to the gallon city. So you can imagine my aggravation with this new development at less than 1k miles.

Any advice would be appreciated, thanks everyone..

[Cayenne97]

ditch the auto i went through 7 of them in 6 months

4L60's can indeed handle copious amounts of power if built right. Sounds like you blew a clutch band. Is the tranny warranteed? If so, I would take it back to whoever bought it and have it replaced!

[z28punk]

clutch band

U mean the 2-4 band?

it wouldnt free rev if it was just a band. it could slip tho.
it might be the crappy Forward sprag that has been notorious in a lot of 04-current 4L60's. if u got a new sprag, then u might have gotten a bad one.
make sure the shop flushed the cooler lines before the rebuilt tranny went back in. crap can stay in there and mess up a new tranny.
as far as the hard shifts... yes PCM is the contoller of that. only other thing that could cause that is stuck valve in the valve body.
bring it back to the shops and have them fix your beast.

[qwk93ta]

PMed you.

[96Firebirdformula]

ditch the auto i went through 7 of them in 6 months

7 in 6 months was you doing neutral drops LOL!!

[Zboner]

4L60's can indeed handle copious amounts of power if built right. Sounds like you blew a clutch band. Is the tranny warranteed? If so, I would take it back to whoever bought it and have it replaced!

i went to trans school know how to build them, i just dont like them at all, look at the auto section of here and tech, so many problems ditch them

[Zboner]

7 in 6 months was you doing neutral drops LOL!!

if you have any amount of power over stock they tend to blow fast

[djvaly]

a4 stg 4 rebuilt twice with shift kit in it etc... $1800, a4 stg 5 once $2100, it hold ok after 3 runs at the track. not sure if it will hold another few runs... you always roll the dice on those stock A4 built up... TH350 or TH400 is a nice upgrade and will hold tons better than 4L60E even if built stage 50000000 ahhaha

[{FzS}BlacKMagicK]

a4 stg 4 rebuilt twice with shift kit in it etc... $1800, a4 stg 5 once $2100, it hold ok after 3 runs at the track. not sure if it will hold another few runs... you always roll the dice on those stock A4 built up... TH350 or TH400 is a nice upgrade and will hold tons better than 4L60E even if built stage 50000000 ahhaha

That crappy? Damn...

Can a TH400 bolt right in or does it require a lot of modification?

I figure there has to be a reason more don't go that route???

[Bottesini]

One of the big disadvantages is the loss of OD, but the TH series is a tried and true tranny. If you dont' won't to worry about breaking that is one of the safest ways to go. I am not sure how easily they take on electronic shifting either.